diff --git a/handler.go b/handler.go
index 0dd2dae..5edffef 100644
--- a/handler.go
+++ b/handler.go
@@ -3,14 +3,12 @@ package htpack
 import (
 	"fmt"
 	"net/http"
-	"os"
 	"path"
 	"path/filepath"
 	"strconv"
 	"strings"
 	"time"
 
-	"golang.org/x/sys/unix"
 	"src.lwithers.me.uk/go/htpack/packed"
 )
 
@@ -21,31 +19,14 @@ const (
 
 // New returns a new handler. Standard security headers are set.
 func New(packfile string) (*Handler, error) {
-	f, err := os.Open(packfile)
+	mapped, err := packed.MapAndLoad(packfile)
 	if err != nil {
 		return nil, err
 	}
-	defer f.Close()
-
-	fi, err := f.Stat()
-	if err != nil {
-		return nil, err
-	}
-	mapped, err := unix.Mmap(int(f.Fd()), 0, int(fi.Size()),
-		unix.PROT_READ, unix.MAP_SHARED)
-	if err != nil {
-		return nil, err
-	}
-
-	_, dir, err := packed.Load(f)
-	if err != nil {
-		unix.Munmap(mapped)
-		return nil, err
-	}
 
 	h := &Handler{
-		mapped:    mapped,
-		dir:       dir.Files,
+		mapped:    mapped.Data,
+		dir:       mapped.Directory.Files,
 		headers:   make(map[string]string),
 		startTime: time.Now(),
 	}